We have discovered a new, potent, selective, and orally active oxytocin receptor antagonist, (2S,4Z)-N-[(2S)-2-hydroxy-2-phenylethyl]-4-(methoxyimino)-1-[(2Ј-methyl[1,1Ј-biphenyl]-4-yl)carbonyl]-2-pyrrolidinecarboxamide (compound 1).We report the biochemical, pharmacological, and pharmacokinetic characterization in vitro and in vivo of this compound. Premature birth is a major problem in obstetrics affecting about 10% of all births and being the largest cause of perinatal morbidity and mortality. The impact on society is significant in terms of costs of neonatal intensive care and for the emotional and social stress to the family. The physiopathology of human preterm labor is complex and multifactorial. Preterm increase of uterine activity is a common complication of pregnancy and accounts for many cases of preterm labor. Pharmacological interventions aimed at maintaining uterine quiescence (tocolysis) have been, and are likely to remain, the cornerstone of pharmaceutical management of preterm labor. However, current tocolytic agents (␤-mimetics, magnesium sulfate, calcium channel blockers, or prostaglandin synthesis inhibitors) suffer from a minimal effectiveness and show important fetal and maternal side effects. Therefore, it is obvious that a safe and effective oral treatment delaying spontaneous preterm birth would have tremendous clinical benefits.The peptide hormone oxytocin (OT) is a potent contractor of the human uterus. OT mediates its effect through activation of the G protein-coupled oxytocin receptor (OT-R) that is expressed in myometrial cells. OT-R is coupled to phospholipase C activation, leading to intracellular synthesis of inositol phosphates and mobilization of calcium. In turn, the rise in intracellular calcium concentration promotes a cascade of events, including phosphorylation of myosin, that then acts on actin and induces uterine muscle cell contraction. Before onset of labor and in the term myometrium, the OT-R density Article, publication date, and citation information can be found at

Phosphodiesterases (PDEs) are a family of enzymes that hydrolyze cyclic nucleotides to render them biologically inactive. As such, these enzymes are critical regulators of signal transduction pathways that use cyclic nucleotides as second messengers. PDE4 is one such member that has been identified in ovarian tissue and purported to have a role in the regulation of gonadotropin action. In the present study, selective PDE4 inhibitors enhanced intracellular signaling in a human LH receptor-expressing granulosa cell line. In vivo, PDE4 inhibition in FSH-primed rats resulted in ovulation, indicating that the PDE4 inhibitors can substitute for LH and human chorionic gonadotropin (hCG) in this process. Moreover, when coadministered with a subeffective dose of hCG, PDE4 inhibitors acted synergistically to enhance the ovulation response. Inhibitors of PDE3 or PDE5 had no ovulatory effect under similar conditions. Oocytes that were ovulated after PDE4 inhibition could be fertilized in vitro at a rate similar to that of oocytes from hCG-induced ovulation. Moreover, such oocytes were fully capable of being fertilized in vivo and developing into normal live pups. These results indicate that small molecule PDE4 inhibitors may be orally active alternatives to hCG as part of a fertility treatment regimen.

Endometriosis is an estrogen (ER)-dependent gynecological disease caused by the growth of endometrial tissue at extrauterine sites. Current endocrine therapies address the estrogenic aspect of disease and offer some relief from pain but are associated with significant side effects. Immune dysfunction is also widely believed to be an underlying contributor to the pathogenesis of this disease. This study evaluated an inhibitor of c-Jun N-terminal kinase, bentamapimod (AS602801), which interrupts immune pathways, in 2 rodent endometriosis models. Treatment of nude mice bearing xenografts biopsied from women with endometriosis (BWE) with 30 mg/kg AS602801 caused 29% regression of lesion. Medroxyprogesterone acetate (MPA) or progesterone (PR) alone did not cause regression of BWE lesions, but combining 10 mg/kg AS602801 with MPA caused 38% lesion regression. In human endometrial organ cultures (from healthy women), treatment with AS602801 or MPA reduced matrix metalloproteinase-3 (MMP-3) release into culture medium. In organ cultures established with BWE, PR or MPA failed to inhibit MMP-3 secretion, whereas AS602801 alone or MPA + AS602801 suppressed MMP-3 production. In an autologous rat endometriosis model, AS602801 caused 48% regression of lesions compared to GnRH antagonist Antide (84%). AS602801 reduced inflammatory cytokines in endometriotic lesions, while levels of cytokines in ipsilateral horns were unaffected. Furthermore, AS602801 enhanced natural killer cell activity, without apparent negative effects on uterus. These results indicate that bentamapimod induced regression of endometriotic lesions in endometriosis rodent animal models without suppressing ER action. c-Jun N-terminal kinase inhibition mediated a comprehensive reduction in cytokine secretion and moreover was able to overcome PR resistance.

We report a novel chemical class of potent oxytocin receptor antagonists showing a high degree of selectivity against the closely related vasopressin receptors (V1a, V1b, V2). An initial compound, 7, was shown to be active in an animal model of preterm labor when administered by the intravenous but not by the oral route. Stepwise SAR investigations around the different structural elements revealed one position, the arenesulfonyl moiety, to be amenable to structural changes. Consequently, this position was used to introduce a variety of substituents to improve the physicochemical properties. Some of the resulting analogues were found to be superior to 7 both in terms of potency in vitro and aqueous solubility, which translated into significantly improved efficacy in the animal model after intravenous and oral administration. The best compound, 73, potently inhibited oxytocin-induced uterine contractions in nonpregnant rats and reduced spontaneous uterine contractions in late-term pregnant rats.

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